Mechanism and product characteristics of pyrolysis-activation coupling reaction of Shenfu coal
-
摘要: 利用两段式固定床反应装置, 研究了神府煤热解-活化耦合产物的特性, 探讨了热解温度及活化剂 (H2O (g)、CO2和H2O (g)/CO2) 对产物性能的影响, 揭示了热解-活化耦合反应机制。结果表明, 热解温度对半焦的CO2化学反应性影响较小; 采用热解-活化两段耦合工艺, 可使神府煤热解的焦油产率明显提高, 产率最高为17.8%;不同活化剂对两段耦合过程产生的混合煤气 (mixture coal gases, MCG) 和焦油产率影响为H2O (g)>H2O (g)/CO2>CO2, 其焦油组分均以饱和分和芳香分为主; 采用H2O (g)/CO2(1:1) 活化剂, 可有效提高活性炭的比表面积, 其BET比表面积为845.37 m2/g。热解-活化耦合机制主要为活化段产生的合成气 (synthesis gases, SG) 为热解段煤的加氢热解提供了氢源, 丰富的氢自由基促进了煤的加氢热解反应, 改变了耦合过程的产物分布和特性。Abstract: The characteristics of products from Shenfu coal pyrolysis-activation coupling reaction were investigated in a two-stage fixed bed reactor.The effect of pyrolysis temperature and activating agents (H2O (g), CO2 and H2O (g)/CO2) on the characteristics of products was analyzed.The mechanism of pyrolysis-activation coupling reaction was revealed.The results show that the pyrolysis temperature has little effect on the CO2 chemical reactivity of the chars.The tar yield of Shenfu coal pyrolysis is significantly increased by using pyrolysis-activation coupling process, and the tar yield is up to 17.8%.The effect of different activating agents on the yield of mixed coal gases (MCG) and tar is in the order of H2O (g)>H2O (g)/CO2>CO2 and the main components of tar are saturates and aromatics.The specific surface area of activated carbon can be effectively improved by using H2O (g)/CO2 as the activating agents, and the BET specific surface area reaches to 845.37 m2/g.The mechanism of pyrolysis-activation coupling process is that the synthesis gases (SG) from the activation section can provide hydrogen source for coal hydropyrolysis in pyrolysis section, and the rich hydrogen radicals can promote the reaction and change the product distribution and properties.
-
Key words:
- Shenfu coal /
- pyrolysis-activation /
- coupling reaction /
- activated carbon /
- tar composition
-
图 1 煤热解-活化耦合工艺流程示意图
Figure 1. Flow chart of the coal pyrolysis-activation coupling
1: gas cylinder; 2: commingler; 3: preheater; 4: control cabinet; 5: furnace; 6: tubular reactor; 7: gas/liquid separator;8: refrigeration cycle; 9: soap bubble flow-meter; 10: dryer; 11: gas chromatograph; 12: heating belt; 13: steam generator
表 1 神府煤的工业分析和元素分析
Table 1. Proximate and ultimate analyses of Shenfu coal
Proximate analysis wad/% Ultimate analysis wdaf/% H/C O/C M A V FC* C H N O* S 5.98 7.26 36.75 50.01 79.86 4.88 0.89 14.09 0.28 0.73 0.13 *: by difference 表 2 半焦的工业分析、元素分析和结构参数
Table 2. Proximate analysis, ultimate analysis and structural parameters of chars
Sample Proximate analysis wad/% Ultimate analysis wdaf/% H/C O/C Structural parameters M A V FC* C H N O* S (mol ratio) fa 2(R-1)/C R Char(N2-500) 1.31 7.98 10.84 79.87 89.02 1.32 0.87 8.53 0.26 0.18 0.07 0.868 0.954 4.900 Char(N2-550) 1.29 8.29 8.21 82.21 89.81 1.22 0.55 8.19 0.23 0.16 0.07 0.886 0.951 4.936 Char(N2-600) 1.29 8.48 7.44 82.79 88.67 1.29 0.78 8.99 0.27 0.17 0.08 0.904 0.922 4.775 Char(N2-650) 1.25 8.72 5.38 84.65 89.51 1.15 0.61 8.49 0.24 0.18 0.07 0.915 0.931 4.855 Char(N2-700) 1.23 9.12 4.73 84.92 89.99 1.01 0.73 8.02 0.25 0.18 0.07 0.913 0.952 4.982 Char(N2-750) 1.19 9.24 4.24 85.33 90.07 0.93 0.66 8.12 0.22 0.16 0.06 0.917 0.959 5.019 *: by difference; fa: aromaticity factor; 2(R-1)/C: ring condensation index; R: even ring condensation number 表 3 半焦和活性炭的比表面积和孔结构
Table 3. Surface area and pore structure parameters of char and activated carbons
Sample BET surface area A/(m2·g-1) Pore volume v/(cm3·g-1) Pore size d/nm BET surface
areamicropore
surface areaexternal
surface areatotal pore
volumemicropore
pore volumeaverage
pore sizeChar 31.82 28.12 3.70 0.059 0.009 53.25 AC (H2O) 725.19 637.14 88.05 0.219 0.079 3.93 AC (H2O/CO2) 845.37 741.59 103.78 0.243 0.061 4.86 AC (CO2) 591.67 530.22 61.45 0.287 0.058 5.72 表 4 活化剂对SG中气体产量的影响
Table 4. Effect of activating agents on yield of gases in SG
Activating agents H2/(mmol·g-1) CH4/(mmol·g-1) CO /(mmol·g-1) CO2/(mmol·g-1) H2O (g) 50.29 1.92 1.15 19.17 H2O (g)/CO2 20.33 1.51 9.32 36.64 CO2 2.86 0.98 17.46 50.71 表 5 活化剂对热解-活化耦合焦油组成的影响
Table 5. Effect of activating agents on component of tar from pyrolysis-activation coupling process
Activation agent Content w/% saturates aromatics rein asphaltene H2O (g) 32.70 49.69 12.85 4.76 H2O (g)/CO2 31.26 50.32 13.70 4.72 CO2 29.97 51.08 13.94 5.01 表 6 神府煤热解-活化耦合反应主要反应及产物
Table 6. Main reactions and product composition of Shenfu coal pyrolysis-activation coupling process
Reaction zone Product composition Gas composition Chemical reaction[24, 25] Activation zone activated carbon H2, CH4, CO, CO2 C (s)+H2O (g) ↔ H2(g)+CO (g)-131.5 kJ/mol C (s)+2H2O (g) ↔2 H2(g)+CO2(g)-88.0 kJ/mol C (s)+CO2(g) ↔ 2CO (g)-172.7 kJ/mol CO (s)+H2O (g) ↔H2(g)+CO2(g)+40.6 kJ/mol Pyrolysis zone tar, gas, char H2, CH4, CO, CO2, C2-4 cracking reaction secondary reaction crosslinking reaction polycondensation -
[1] 甘建平, 马宝岐, 尚建选, 马晓迅, 杨占彪.煤炭分质转化理念与路线的形成和发展[J].煤化工, 2013, (1):3-6. http://www.cnki.com.cn/Article/CJFDTOTAL-MHGZ201301002.htmGAN Jian-ping, MA Bao-qi, SHANG Jian-xuan, MA Xiao-xun, YANG Zhan-biao.Formation and development of the coal grading conversion ideas[J].Coal Chem Ind, 2013, (1):3-6. http://www.cnki.com.cn/Article/CJFDTOTAL-MHGZ201301002.htm [2] 李保庆.煤加氢热解研究I.宁夏灵武煤加氢热解的研究[J].燃料化学学报, 1995, 23(1):57-61. http://www.cnki.com.cn/Article/CJFDTOTAL-RLHX501.009.htmLI Bao-qing.Hydropyrolysis of Chinese coals I.Hydropyrolysis of LingWu bituminous coal[J].J Fuel Chem Technol, 1995, 23(1):57-61. http://www.cnki.com.cn/Article/CJFDTOTAL-RLHX501.009.htm [3] 王鹏, 文芳, 步学朋, 刘玉华, 边文, 邓一英.煤热解特性研究[J].煤炭转化, 2005, 28(1):8-13. http://www.baidu.com/link?url=DxXumxDdQiihzwlgTnkhN8wlYXBxaCMzajl7Lz6HeloTFlw9xQU_ZJ7gETCEQGQz6ZIuiGrA60WxEwQ6wcCrmrqEF3RXWsynuPoR-pEYVjwyCqzsyGpvg2_mBpp_VumBN78GOwTzQJqpcIKZZb42Fiz4AdavMDi8_v8FIwdK6aJO9btDnOa4jMPUr7o-Zj-qgNCP7PUNnld8fO4gVAP9AP3djkMsfE3ldagzxuNt9hbgaEPzJrqS64L61JE1xEq03sSNVNFyB6pRbW3NfKNok8KzuDCNVoLx3nparWARQ0Swojhypv0Aco-Py10ZEMfmwsDvQwG82dpq1OFlFFyaGK&wd=&eqid=bff03c61000411e00000000558bfddb3WANG Peng, WEN Fang, BU Xue-peng, LIU Yu-hua, BIAN Wen, DENG Yi-ying.Study on the pyrolysis characteristics of coal[J].Coal Convers, 2005, 28(1):8-13. http://www.baidu.com/link?url=DxXumxDdQiihzwlgTnkhN8wlYXBxaCMzajl7Lz6HeloTFlw9xQU_ZJ7gETCEQGQz6ZIuiGrA60WxEwQ6wcCrmrqEF3RXWsynuPoR-pEYVjwyCqzsyGpvg2_mBpp_VumBN78GOwTzQJqpcIKZZb42Fiz4AdavMDi8_v8FIwdK6aJO9btDnOa4jMPUr7o-Zj-qgNCP7PUNnld8fO4gVAP9AP3djkMsfE3ldagzxuNt9hbgaEPzJrqS64L61JE1xEq03sSNVNFyB6pRbW3NfKNok8KzuDCNVoLx3nparWARQ0Swojhypv0Aco-Py10ZEMfmwsDvQwG82dpq1OFlFFyaGK&wd=&eqid=bff03c61000411e00000000558bfddb3 [4] WANG P F, JIN L J, LIU J H, ZHU S W, HU H Q.Analysis of coal tar derived from pyrolysis at different atmospheres[J].Fuel, 2013, 104(2):14-21. http://www.baidu.com/link?url=dkIEjWOflfQb7gL6VfZbSbipb6B7jM0TW6RnEgS0xsd-vBOV4ohOIiy5UddpnUY_piGkpwyZMf8Kpfc2H5GFD92jp-QqikpcFCvQcFNUekSSlL5YtFEA8Zmyhvg4BGVOUInYHNzPEISTHWkgn0WW_N3faBu_Z3LhdZbiKEWgiuyJNOSAUzMouAwiC-yQxF7ClalpkGD4lrmvVvub_2fZSQGTT96iyToYyisrr0yS8XOaRZxGm5JdL9qDHGA2Oyzztz6Q2A0RyqO78JbMFJh0t6q3wJwHcp4uH26sqJNtBL-8am6jFvwqA4NWacbX6mJjrzfmNhBGWj_2eQj8vMje8q&wd=&eqid=ba5cc9630003fefd0000000558bfddc5 [5] FIDALGO B, VAN NIEKERK D, MILLAN M.The effect of syngas on tar quality and quantity in pyrolysis of a typical South African inertinite-rich coal[J].Fuel, 2014, 134(15):90-96. http://www.baidu.com/link?url=ndm3qJFq2lvtxztbVOFvXuzH72v2iRcP9TbElucylo8uJ3M-5RXGNlPHtnKqr7K9IMHC6qe3EWkMlithIY8BHrnk_2TDpTxqiRmtZ80FdIFNAHNcW57HsFm1EI-cf_ptTBMGXSTySFxCJqyW44Wo0gPTn3sdFI2I6dw8U1mHlKyQAtwBWxOPHpcErCmlKxkcyz2Zj0alRU35d-d2eSUpMvebLO63j-2D96-LhUlZQ_gMxsf3ycvs0WBTOQnSYm35M26f97--pobA80bDaIih_MdNQUCGMFM7j3OsafJYz7EgmWnN3ToO4rbALgIQNLZcx-kWPNLNQUPU_0jiNhOFvtVdikex2KjlCd3SJOo7neaTFCEJQv8cOwEHN60Ae6wNPzg14oV8vigNpOHdpYNd3a&wd=&eqid=bed56a090003d2650000000558bfddd2 [6] 高超, 马凤云, 马空军, 黄黎明, 钟梅.热解气氛对煤催化热解焦油品质的影响[J].煤炭学报, 2015, 40(8):1956-1962. http://www.cnki.com.cn/Article/CJFDTOTAL-MTXB201508036.htmGAO Chao, MA Feng-yun, MA Kong-jun, HUANG Li-ming, ZHONG Mei.Effect of pyrolysis gas on the tar quality from coal catalytic pyrolysis[J].J Chin Coal Soc, 2015, 40(8):1956-1962. http://www.cnki.com.cn/Article/CJFDTOTAL-MTXB201508036.htm [7] 李晶.神府半焦催化活化及多联产研究[D].西安:西安科技大学, 2010.LI Jing.Study on catalytic activation and poly-generation of Shenfu semi-coke[D].Xi'an:Xi'an University of Science and Technology, 2012. [8] 周安宁, 张洪利, 赵世永, 张亚婷, 任秀彬, 刘源.连续式梯级热解-活化耦合多联产移动床:中国CN202039028U[P].2011-11-16.ZHOU An-ning, ZHANG Hong-li, ZHAO Shi-yong, ZHANG Ya-ting, REN Xiu-bin, LIU Yuan.Continuous cascade pyrolysis-activation coupled multi-generation moving bed:CN, 202039028U[P].2011-11-16. [9] GB/T 480-2010.煤的铝甑低温干馏试验方法[S].北京:中国标准出版社, 2010.GB/T 480-2010.Test of low temperature distillation of coal by aluminum retort[S].Beijing:China Standard Press, 2010. [10] GB/T 220-2001.煤对二氧化碳化学反应性的测定方法[S].北京:中国标准出版社, 2010.GB/T 480-2010.Determination of carboxy reactivity of coal[S].Beijing:China Standard Press, 2001. [11] NB/SH/T 0509-2010.石油沥青四组分测定法[S].北京:中国石化出版社, 2010.NB/SH/T 0509-2010.Test method for separation of asphalt into four fractions[S].Beijing:China Petrochemical Press, 2010. [12] WANG J, DU J, CHANG L P, XIE K Cl.Study on the structure and pyrolysis characteristics of Chinese western coals[J].Fuel Process Technol, 2010, 91(4):430-433. doi: 10.1016/j.fuproc.2009.04.020 [13] 刘源, 贺新福, 杨伏生, 张亚刚, 任秀彬, 周安宁.热解温度及气氛变化对神府煤热解产物分布的影响[J].煤炭学报, 2015, 40(S2):497-504. http://www.cnki.com.cn/Article/CJFDTOTAL-MTXB2015S2028.htmLIU Yuan, HE Xin-fu, YANG Fu-sheng, ZHANG Ya-gang, REN Xiu-bin, ZHOU An-ning.Impacts of pyrolysis temperature and atmosphere on product distribution of Shenfu coal pyrolysis[J].J Chin Coal Soc, 2015, 40(S2):497-504. http://www.cnki.com.cn/Article/CJFDTOTAL-MTXB2015S2028.htm [14] CEYHAN A A, ŞAHIN Ö, BAYTAR O, SAKA C.Surface and porous characterization of activated carbon prepared from pyrolysis of biomass by two-stage procedure at low activation temperature and it's the adsorption of iodine[J].J Anal Appl Pyrolysis, 2013, 104(11):378-383. [15] JAYARAMAN K, GOKALP I.Effect of char generation method on steam, CO2 and blended mixture gasification of high ash Turkish coals[J].Fuel, 2015, 153:320-327. doi: 10.1016/j.fuel.2015.01.065 [16] LI T T, ZHANG L, DONG L, LI C Z.Effects of gasification atmosphere and temperature on char structural evolution during the gasification of Collie sub-bituminous coal[J].Fuel, 2014, 117(1):1190-1195. http://www.baidu.com/link?url=ZJ3DEX6GZT1E-bP6ZYS2fV8zVOKkYjQUy0yW2tjP6XAKu3wcKVVLVyllC4K41MHOBLzTXQOjYu0WgIJgP3KGHPwHA6WON3D2ekwjJHytrXWE4B10niSQUVOnZmu_jN91xc9Q4P63BssnizjaXzv5AUKKomihEe5ImO-NA9S_wq5qZPXVVgFQ8KcDZeJB5P5db6za6VPKtgX-IwoKUfT3HImC2o-pgR3sQxwFyGPS-meq_euUykfMSdmCuR3MOjGZNEqkuFljHYP6MxY7_QVMmv_5EnYsXBxYvu1hO7bEvz8X-8dBBYYuyhkTI6SDWbTxX8Eed2mauWY0jxZYo7oLP4PMC43WXbogo5dFjbwDqseB7s-QJnYM45mU-aF6Z4KiFC0oeCK9P0pb5B8BqsLQAYbnk6HZQuVrduK49IfPehe&wd=&eqid=be4800dd00039f6b0000000558bfddfb [17] 郭文涛, 王静松, 佘雪峰, 薛国庆, 郭占成.焦炭与CO2和水蒸气气化后孔隙结构和高温抗压强度研究[J].燃料化学学报, 2015, 43(6):654-662. http://rlhxxb.sxicc.ac.cn/CN/abstract/abstract18637.shtmlGUO Wen-tao, WANG Jing-song, SHE Xue-feng, XUE Guo-qing, GUO Zhan-cheng.Pore structure and high-temperature compressive strength of gasified coke with CO2 and steam[J].J Fuel Chem Technol, 2015, 43(6):654-662. http://rlhxxb.sxicc.ac.cn/CN/abstract/abstract18637.shtml [18] GUIZANI C, SANZ F J E, SALVADOR S.Influence of temperature and particle size on the single and mixed atmosphere gasification of biomass char with H2O and CO2[J].Fuel Process Technol, 2015, 134:175-188. doi: 10.1016/j.fuproc.2015.01.031 [19] 贺新福.甲烷低温等离子体活化与煤热解耦合过程研究[D].大连:大连理工大学, 2012.He Xin-fu.Integrated process of coal pyrolysis with methane activation by cold plasma[D].Dalian:Dalian University of Technol, 2012. [20] TANNER J, BLÄSING M, MVLLER M, BHATTACHARYA S.The temperature-dependent release of volatile inorganic species from Victorian brown coals and German lignites under CO2 and H2O gasification conditions[J].Fuel, 2015, 158:72-80. doi: 10.1016/j.fuel.2015.04.071 [21] 谢克昌.煤的结构与反应性[M].北京:科学出版社, 2002:287-280.XIE Ke-chang.Coal structure and its reactivity[M].Beijing:Science Press, 2002:287-280. [22] 贺孟霜.道路石油沥青结构行为与性能表征[D].西安:长安大学, 2013.HE Meng-shuang.Structure behaviors and properties characterization for paving asphalt[D].Xi'an:Chang'an University, 2013. [23] 钟梅, 马凤云.不同气氛下煤连续热解产物的分配规律及产品品质分析[J].燃料化学学报, 2013, 41(12):1427-1436. http://rlhxxb.sxicc.ac.cn/CN/abstract/abstract18308.shtmlZHONG Mei, MA Feng-yun.Analysis of product distribution and quality forcontinuous pyrolysis of coal in different atomspheres[J].J Fuel Chem Technol, 2013, 41(12):1427-1436. http://rlhxxb.sxicc.ac.cn/CN/abstract/abstract18308.shtml [24] DONG C, JIN L, TAO S, LI Y, HU H.Xilinguole lignite pyrolysis under methane with or without Ni/Al2O3 as catalyst[J].Fuel Process Technol, 2015, 136(8):112-115. [25] 张德祥.煤制油技术基础与应用研究[M].上海:上海科学技术出版社, 2013:87-90.ZHANG De-xiang.Fundamental and application of coal to oil technologies[M].Shanghai:Shanghai Science & Technical Publishers, 2013:87-90.